This application makes reference to, incorporates the same herein, and claims all benefits s accruing under 35 U.S.C xc2xa7119 from an application entitled Method And Apparatus For Displaying Sub-Pictures earlier filed in the Korean Industrial Property Office on Nov. 5, 1997, and there duly assigned Serial No. 97-58135 by that Office.
1. Field of the Invention
The present invention relates to a method and apparatus for displaying a sub-picture together with a main picture. More particularly, the invention relates to a method and apparatus for varying the state of a sub-picture according to a complexity and a degree of movement of a main picture when a video signal compressed by a video compression standard, such as MPEG (Motion Picture Experts Group) standard, is reproduced as the main picture.
2. Description of the Related Art
In general, as reproduction apparatuses having a sub-picture display function, there are digital media reproduction apparatuses, such as a digital versatile disc (DVD) player, a video compact disc (CD) player, and a digital video signal reproduction apparatus utilizing the motion picture compression standard. Typically, a reproduction apparatus having a sub-picture display function displays a sub-picture on a main picture as shown in FIG. 3. Examples of reproduction apparatus having a sub-picture display function are provided by the following patents, incorporated by reference herein: U.S. Pat. No. 5,361,098 to Keith Lucas entitled Methods And Apparatus For Generating A Picture-In-Picture Digital Television Frame By Inserting A Mean-Only Frame Into A Full-Size Frame; U.S. Pat. No. 5,386,241 to Hak-Jae Park entitled Signal Transformation System And Method for Providing Picture-In-Picture In High Definition Television Receivers; U.S. Pat. No. 5,594,507 to W. Leo Hoarty entitled Compressed Digital Overlay Controller And Method For MPEG Type Video Signal; and U.S. Pat. No. 5,614,952 to Jill M. Boyce et al. entitled Digital Video Decoder for Decoding Digital High Definition And/Or digital Standard Definition Television Signals.
When the state of a main picture is complicated or the amount of movement thereof is large, an existing reproduction apparatus has a problem that a sub-picture is not definitely discerned from a main picture.
To solve the above problem, it is an object of the present invention to provide a method and apparatus for displaying a sub-picture in which the display state of the sub-picture is varied according to an image complexity and/or a degree of movement of a main picture, to thereby allow the sub-picture to be always distinct irrespective of the image state of the main picture.
To accomplish the above object of the present invention, there is provided a picture display method for displaying a sub-picture together with a main picture. The picture display method comprising the steps of (a) detecting a state of the main picture from an encoded main picture signal; (b) decoding the encoded main picture signal; and (c) signal-processing an input sub-picture signal and the main picture signal obtained in the step (b) based upon the main picture state detected in the step (a), to display sub-picture and the main picture so as to discern the sub-picture from the main picture.
There is also provided a picture display apparatus for displaying a sub-picture together with a main picture. The picture display apparatus comprises a detector for detecting a state of the main picture from an encoded main picture signal; a signal processor for decoding the encoded main picture, and signal-processing and outputting an input sub-picture signal and the main picture signal, in order to display main picture together with sub-picture; and a controller for controlling the operation of the signal processor based upon the main picture state detected in the detector so that the sub-picture is distinguished from the main picture.